Magnetosphere - Ionosphere Coupling Below
3000 km: Conversion of
Upwelling Ions to Escaping Ions
or
If O+ is important in the magnetosphere, how
does it get out of the ionosphere?
Paul M. Kintner, Jr.
with the help of
R. Arnoldy, K. Lynch, K. Frederick-Frost, E. Klatt, J-E.
Wahlund, J. Moen, A. Strømme, Y. Ogawa, K.
Oksavik, W. Swartz + many others
But first
an unashamed advertisement
• Chapman Conference on Midlatitude
Ionospheric Dynamics and Disturbances
• January 3-6, 2007
• Yosemite, California
• http://www.agu.org/meetings/cc07acall.ht
ml
• Abstract deadline- September 15, 2006
Outline
• Motivation for investigating ionospheremagnetosphere mass coupling
• Mechanisms of O+ escape from the ionosphere to
the magnetosphere
• Radar viewpoint (up to roughly 800 km altitude)
• LEO Satellite viewpoint (near 850 km altitude)
• Sounding rocket viewpoint (up to 1400 km
altitude)
• Modeling viewpoint
• The next step- SCIFER 2
Motivation
O+ in the Plasma Sheet
Nosé, M., R. W. McEntire,
and S. P. Christon (2003),
Change of the plasma sheet
ion composition during
magnetic storm development
observed by the Geotail
spacecraft, J. Geophys.
Res., 108(A5), 1201,
doi:10.1029/2002JA009660.
Motivation
O+ in the Ring Current
Daglis, I. A., R. M. Thorne,
W. Baumjohann, and S.
Orsini (1999), The terrestrial
ring current: Origin,
formation, and decay, Rev.
Geophys., 37(4), 407–438.
Motivation
O+ Effect on Polar Cap Potential
Winglee, R. M., D. Chua, M.
Brittnacher, G. K. Parks, and
G. Lu, Global impact of
ionospheric outflows on the
dynamics of the
magnetosphere and crosspolar cap potential, J.
Geophys. Res., 107(A9),
1237,
doi:10.1029/2001JA000214,
2002
Mechanisms of O+ Escape
• IRI-2001
Ionosphere for
pre-noon cleft in
darkness over
EISCAT, Svalbard
at solar minimum
• O+ is mostly below
1000 km
• Ti≈1500 °K
• Te≈3000 °K
MODEL
Mechanisms of
+
O
Escape
Gravitational Binding Energy
Set KE=PE
1 2 GMm
mv =
2
r
r = (6371 + 1000 ) ⋅105 cm
G = 6.7 ⋅10 −8 dyne ⋅ cm 2 /g 2
M = 6 ⋅10 27 g
Escape Velocity v = 10.4 ⋅105 cm/s
Energy
for O+
1 2
−12
3 o
mv = 13.9 ⋅10 ergs = 8.7 eV = 101 ⋅10 K
2
Mechanisms of O+ Escape
Mean Free Path
•
At 500 km O+
decouples from
neutrals
• At 900-1000 km
O+ decouples
from O+
• O+ never
decouples from
H+ unless H+
density less than
IRI model
Mechanisms of O+ Escape
Summary
• Frictional heating in strong horizontal flows producing
either elevated Ti or toroidal phase space distributions
(T┴>T║)
– Called Type 1 by Wahlund et al. [1992]
• Soft precipitating electrons heat ionospheric electron gas
which expands pulling ions along through ambipolar
field.
– Called Type 2 by Wahlund et al. [1992]
• Transverse ion acceleration/heating by BBELF waves
– Waves are presumed to be a combination of electrostatic ion
cyclotron waves and ion acoustic waves driven by FAC
Mechanisms of O+ Escape
Overview
• Where is transition
between ion
upwelling and wave
heating? What are
their relative roles?
• How do FAC (via
Poynting flux) fit into
this picture?
After Strangeway et al.
[2005]
Where Does One Go to Investigate
Ion Outflows?
• FAST measurements
of ion outflows
• Andersson et al, 2006
• 3200-4400 km alt.
• Ion outflow flux from
all measurements
Radar Viewpoint
• EISCAT radar and EISCAT Svalbard Radar (ESR)
• EISCAT is tristatic UHF and single VHF
• ESR has a fixed antenna along B and a steerable
antenna
• Information is created by modeling echo return
–
–
–
–
Doppler shift yields ion drift velocity
Spectral shape yields Ti, Te/Ti, <Mi>, νin
Amplitude yields density
Also possible to have non-thermal or enhanced echoes which
are coherent scattering from plasma waves
– Time delay yields range
– No echoes when wavelength exceeds Debye length
Radar Viewpoint
Echo modeling
Radar Viewpoint
Five parameters yield
shape and amplitude
of echo spectrum
FFT(Echo)
Additionally Doppler
shift yields bulk ion drift
velocity in line of sight
thanks to Gudmund Wannberg
for figure
Radar Viewpoint-UHF Tristatic
Type 1
Upflowing ions
Radar Viewpoint-UHF Tristatic & VHF
UHF
Type 2 VHF (note different alt. scale)
Radar Viewpoint
EISCAT Svalbard Radar (ESR)
Pink is
good
SERSIO launch
Radar Viewpoint
Ion Temperature Anisotropic (TIA?)
Outflow events
NEIALS
TiVHF> Ti║
ESR (Ti║)
Ogawa et al., 2000
VHF radar
(TiVHF)
LEO Satellite Viewpoint
• Plasma properties
measured with plasma
drift meter or segmented
retarding potential
analyzer
• Yields mean or bulk cross
track drift in horizontal
and vertical directions
• Drifts need to be fraction
of orbital velocity (7 km/s)
LEO Satellite Viewpoint
Outflowing ions
Down
flowing
ions
Elevated
Ti
(or perhaps
ion conic)
Loranc et al. 1981
LEO Satellite Viewpoint
Cusp/Cleft
Outflowing
ions
Fieldaligned
currents
Sounding
Rocket
Viewpoint
Sounding of the Cleft
Ion Fountain
Energization Region
(SCIFER)
Launched 1995 before
ESR was built
Apogee 1452 km over
Svalbard
Sounding Rocket Viewpoint
• Apogee at 700 s
• Ne tracked by plasma
frequency emissions
• Strong correlation
between low
densities, BBELF
waves, and ion
conics (TIA)
• Examine boundary at
765 s next
Sounding Rocket Viewpoint
Sounding Rocket Viewpoint
BBELF Wavelength
Model Viewpoint
• Electron precipitation
1.75 ergs/cm2 at
<E>=300 eV
• Convection 50mV/m
• Downward heat flux
9x109 eV/cm2-s
• Fluid model
Seo, Y., J. L. Horwitz, and R. Caton (1997), Statistical relationships
between high-latitude ionospheric F region/topside upflows and their
drivers: DE 2 observations, J. Geophys. Res., 102(A4), 7493–7500.
Modeling Viewpoint
•
•
•
Zettergren and Semeter at CEDAR
Model ionospheric response to soft electron precipitation
Result is increased Te, ambipolar E, and O+ outflow
Turn on soft electron precipitation
Model Viewpoint
• “…combined effects of the
soft electron precipitation
at F-region/topside
ionosphere and wave
heating at higher altitudes
considerably enhanced
the O+ outflow at higher
altitudes.”
• Tu et al. [2004]
Summary- Cautions
• The ions lie (reflect history not instant in time)
– 1000 m/s upflowing ion takes 10 minutes to climb 600 km during
which the environment can change dramatically
• Bulk measurements (ESR, plasma drift meters) average
over entire distribution function and may disguise nonthermal distributions and wave-particle interactions
• Rockets get snapshot of a biased event and do not make
bulk measurements although they are getting better
• Correlations do not imply causality
• Interpretations depend on the physical
observables obtained from
a specific technique
Where do viewpoints agree?
•
Upward ion velocities
– Radar: 200-600 m/s (higher velocities at higher altitudes)
– LEO Sat: 500-1000 m/s
– Supported by Zettergren and Semeter model
•
Ion fluxes
–
–
–
–
•
Radar: 5x109 cm-2s-1
LEO Sat: 1-10x109 cm-2s-1
Rocket: 8x108 cm-2s-1 (all above 6 eV as ion conic)
Agrees with Z and S model
Electron temperature increases
– Radar: Te≈ 6000°
– Rocket : Te≈ 6000°
– Agrees with Z and S model
•
Ion temperature increases
– Radar: Ti≈ 4000°
– Rocket : Ti≈ 4000° but also TIA and ion conics
– Z and S model predicts 6000° but this may be because of long period of energy
input
Where do viewpoints disagree?
• Ionospheric density
– Radar and Z and S model say density increases: 105 cm-3
– LEO satellites and rocket say density decreases: <103 cm-3
• Large electric fields/drifts
– Radar: Type 1 events
– LEO sat: Not clear
– Rocket: Large drifts in neighborhood but not coincident
• Precipitating soft electrons
– Radar: Implied by increased electron density and temperature
– LEO sat: Cusp precipitation
– Rocket: Precipitating soft electrons in neighborhood but not
coincident
So what is needed to resolve these
apparent contradictions?
• An experiment that measures thermal populations,
suprathermal populations, fields, waves, and FAC
(SCIFER-2 sounding rocket)
• Continued modeling from the Zetergren and Semeter
viewpoint
• Understanding and modeling of how BBELF waves are
created and transversely accelerate ions
• Understanding the time dependence and evolution
– Does Type 1 or 2 prime the pump for TIA?
– Does TIA eat into the ionosphere expelling ions regardless of
Type 1 or 2 contribution to outflows
– Can Type 1 or 2 supply plasma with no TIA
Next Step SCIFER-2
Thermal electrons
Magnetometer for
field-aligned
currents
Instrument
Parameter
Heeps-e
Energetic Electrons
Heeps-M
Ions Mid-Energy
Heeps-T
Ions Thermal
Beeps-T
Thermal Ion Mass
energy [eV]
5-16000
7-800
0.1-20
0.1-20
Number pitch angle bins
30
64
64
16
bin width deg
6 or 18
5
5
20
delta E/E [%]
15
20
10
10
G [cm2-ster-keV/keV/bin]
2e-4
1e-3
5e-5
2e-4
Extra Slides
Summary- Observations
Observation
ESR/EISCAT
LEO Sat
Rocket
Upflow velo.
≈ 1000 m/s
≈ 1000 m/s
?? nightside*
Large ┴ drifts
Yes
Yes
No (nearby)
Te Increase
Yes
Yes
Yes
Ti Increase
Yes but contaminated
Yes
NA*
Ne
Increases
Decreases
Decreases
TIA (conics)
Maybe
NA
Yes
BBELF
?? (NEIALS)
NA
Yes
FAC
NA
Yes
NA*
<1keV electrons
NA
Yes
No (nearby)
Fluxes
5x109 cm-2s-1
1-10x109 cm-2s-1
8x108 cm-2s-1
Increased scale ht. vs. TIA and
wave particle interactions?
•
Evidence for waves
–
–
–
•
Direct rocket observations of BBELF
Radar Naturally Enhanced Ion Acoustic Waves
(NIEALS) which my be related to BBELF
LEO Satellite measurement of field-aligned currents
required to create BBELF
Evidence for TIA (ion conics)
–
–
Direct rocket observations
VHF radar showing that T┴>T║
References
References 1
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Andersson, L., W.K. Peterson, and K.M. McBryde (2005), Estimates of the suprathermal O+ outflow characteristic
energy and relative location in the auroral oval, Geophys. Res. Lett., 32, L09104, doi:10.1029/2004GL021434.
Arnoldy, R.L., K.A. Lynch, P.M. Kintner, J. Bonnell, T.E. Moore, C.J. Pollock (1996), SCIFER–Structure of the cleft
ion fountain at 1400 km altitude, Geophys. Res. Lett., 23(14), 1869-1872.
Chappell, C.R., T.E. Moore, and J.H. Waite Jr. (1987), The ionosphere as a fully adequate source of plasma for
the Earth’s magnetosphere, J. Geophys. Res., 92(A6), 5896–5910.
Coley, W.R., R.A. Heelis, and M.R. Hairston (2003), High-latitude plasma outflow as measured by the DMSP
spacecraft, J. Geophys. Res., 108(A12), 1441, doi:10.1029/2003JA009890.
Daglis, I.A., R.M. Thorne, W. Baumjohann, and S. Orsini (1999), The terrestrial ring current: Origin, formation, and
decay, Rev. Geophys., 37(4), 407–438.
Foster, C., M. Lester, and J.A. Davies (1998), A statistical study of diurnal, seasonal, and solar cycle variations of
F-region and topside auroral upflows observed by EISCAT between 1984 and 1996, Ann. Geophys., 16, 11441158.
Horwitz, J.L. and T.E. Moore (1997), Four contemporary issues concerning ionospheric plasma flow to the
magnetosphere, Space Sci. Rev., 80, 49-76.
Kintner, P.M., J. Bonnell, R. Arnoldy, K. Lynch, C. Pollock, T. Moore, J. Holtet, C. Deehr, H. Stenbaek-Nielsen, R.
Smith, J. Olson, and J. Moen (1996a), The SCIFER Experiment, Geophys. Res. Lett., 23(14), 1865-1868.
Kintner, P.M., J. Bonnell, R. Arnoldy, K. Lynch, C. Pollock and T. Moore (1996b), SCIFER–Transverse ion
acceleration and plasma waves, Geophys. Res. Lett., 23(14), 1873-1876.
References 2
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Loranc, M., W.B. Hanson, R.A. Heelis, and J.-P. St.-Maurice (1991), A morphological study of vertical ionospheric
flows in the high-latitude F region, J. Geophys. Res., 96(A3), 3627-3646.
Lynch, K., R. Arnoldy, P. Kintner, and J. Bonnell (1996), The AMICIST auroral sounding rocket: A comparison of
transverse ion acceleration mechanisms, Geophys. Res. Lett., 23(23), 3293-3296.
Nosé, M., R.W. McEntire, and S.P. Christon (2003), Change of the plasma sheet ion composition during magnetic
storm development observed by the Geotail spacecraft, J. Geophys. Res., 108(A5), 1201,
doi:10.1029/2002JA009660.
Ogawa, Y., R. Fujii, S.C. Buchert, S. Nozawa, S. Watanabe, and A.P. van Eyken (2000), Simultaneous EISCAT
Svalbard and VHF radar observations of ion upflows at different aspect angles, Geophys. Res. Lett., 27(1), 81–84.
Ogawa, Y., R. Fujii, S.C. Buchert, S. Nozawa, and S. Ohtani (2003), Simultaneous EISCAT Svalbard radar and
DMSP observations of ion upflow in the dayside polar ionosphere, J. Geophys. Res., 108(A3), 1101,
doi:10.1029/2002JA009590.
Moore, T. E., C. J. Pollock, M. L. Adrian, P. M. Kintner, R. L. Arnoldy, K. A. Lynch, and J. A. Holtet (1996), The
cleft ion plasma environment at low solar activity, Geophys. Res. Lett., 23(14), 1877–1880.
Pollock, C. J., T. E. Moore, M. L. Adrian, P. M. Kintner, and R. L. Arnoldy (1996), SCIFER—Cleft region thermal
electron distribution functions, Geophys. Res. Lett., 23(14), 1881–1884.
Seo, Y., J.L. Horwitz, and R. Caton (1997), Statistical relationships between high-latitude ionospheric F
region/topside upflows and their drivers: DE 2 observations, J. Geophys. Res., 102(A4), 7493–7500.
Strangeway, R.J., R.E. Ergun, Y.-J. Su, C.W. Carlson, and R.C. Elphic (2005), Factors controlling ionospheric
outflows as observed at intermediate altitudes, J. Geophys. Res., 110, A03221, doi:10.1029/2004JA010829.
Tu, J., J.L. Horwitz, and T.E. Moore (2005), Simulating the cleft ion fountain at polar perigee altitudes, J. Atmos.
Solar-Terr. Phys., 67(5), 465-477.
Tu, J.-N., J.L. Horwitz, P.A. Nsumei, P. Song, X.-Q. Huang, and B.W. Reinisch (2004), Simulation of polar cap
field-aligned electron density profiles measured with the IMAGE radio plasma imager, J. Geophys. Res., 109,
A07206, doi:10.1029/2003JA010310.
References 3
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Wahlund, J.-E., H.J. Opgenoorth, I. Häggström, K.J. Winser, and G.O.L. Jones (1992), EISCAT observations of
topside ionospheric ion outflows during auroral activity: Revisited, J. Geophys. Res., 97(A3), 3019–3037.
Winglee, R.M., D. Chua, M. Brittnacher, G.K. Parks, and G. Lu (2002), Global impact of ionospheric outflows on
the dynamics of the magnetosphere and cross-polar cap potential, J. Geophys. Res., 107(A9), 1237,
doi:10.1029/2001JA000214.
Wu, X.-Y., J. L. Horwitz, and J.-N. Tu (2002), Dynamic fluid kinetic (DyFK) simulation of auroral ion transport:
Synergistic effects of parallel potentials, transverse ion heating, and soft electron precipitation, J. Geophys. Res.,
107(A10), 1283, doi:10.1029/2000JA000190
Extra slides
SERSIO Aurora
SCIFER 2